fix(loyalty): terminal icons, server-side i18n, category in transactions

- Fix icons: plus-circle → plus, backspace → arrow-left
- Convert terminal $t() calls to server-side _() for card_label,
  stamps_until_reward, reward_label, not_enough_stamps
- Inject transaction type labels as server-rendered window._txLabels
  object (eliminates all async i18n warnings on terminal page)
- Resolve category_names in store transactions list endpoint

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/loyalty/routes/api/store.py

@@ -652,11 +652,22 @@ def list_store_transactions(
         db, merchant_id, skip=skip, limit=limit
     )
 
+    from app.modules.loyalty.services.category_service import category_service
+
     tx_responses = []
     for t in transactions:
         tx = TransactionResponse.model_validate(t)
         if t.card and t.card.customer:
             tx.customer_name = t.card.customer.full_name
+        if t.category_ids and isinstance(t.category_ids, list):
+            names = []
+            for cid in t.category_ids:
+                name = category_service.validate_category_for_store(
+                    db, cid, t.store_id or 0
+                )
+                if name:
+                    names.append(name)
+            tx.category_names = names if names else None
         tx_responses.append(tx)
 
     return TransactionListResponse(transactions=tx_responses, total=total)